#wind glider

This post is in response to reblog from @canonical-transformation and asks from @followfire and @beingatoaster

Chapter 1) How the hell does a Tengu Work?

ok that might seem like a strange place to start but I think it’s important to start off with the fact that Tengu wing anatomy is wack as hell. Typically I am the sort of person who likes to do research while thinking about my silly silly headcanons. I have learned a lot about old fabric skinned aircraft and have an appreciation for early heavier than air gliders now because of the (Wikipedia) research I’ve done to think about gliders in genshin. So I figured we’ll look up animals with 4 wings and figure out how they would fly and okay yup, early birds and flying insects. Do any of them have shorter front wings and larger back wings? No? No they are all either larger front or equal size? Excellent. Sounds great. It does seem to be a design feature used in certain types of military jets and missiles to uh… help with turning? I don’t 100% know. It’s called Canard configuration. It’s specifically for fixed wing aircraft and not… birds….

ok so I don’t actually know the motion a tengu’s wings would probably be making. It’s not like we ever get to see them fly in game. Hell, we barely get to see Sara’s wings because the game magically puts them away so they don’t have to animate them except in her idle. This is stupid and we are going to pretend she can’t put her wings away in her inventory and simply just keeps them folded a majority of the time. Anyways enough about Sara for now (don’t worry man. We’ll be back), it’s time for assumption #1: tengus fly in a mostly horizontal position and flap their wings in a rhythm similar to dragonflies (front and back set flap with off timing), but with more elbow in it like a bird. There is a flapping motion, the wings work independently of one another, and a tengu can not hover or fly backwards.

Assumption 2: the larger bottom set is likely responsible for most of the lift. The smaller top set is likely responsible for steering? Especially sharper turns and maneuvers? I don’t 100% know. I really feel like they should be reversed so I can take inspiration from proto-birds like micro raptor but instead we have that. So we are going to work with it.

assumption 3: the human form isn’t really meant to sustain flight? But we know they can fly, and it’s described as flight and not as gliding in lore, and thus they must be able to, for some amount of time, generate enough lift to gain elevation. In order to help reach that goal, a few other things I presume about tengus are that they have extra musculature in and around their wings to support them, they have bones that are more hollow than the average human, both to reduce weight and to store oxygen so that anaerobic metabolism is delayed and thus lactic acid production, allowing tengus to perform athletic feats for longer without exhaustion than an equivalent human, and that their builds tend towards lean and muscular without excessive weight. Sara is a decent example of a tengu build I think! Sort of lanky and isn’t muscular like Itto, where it’s very obvious, but she is muscular and very strong.

those assumptions are going to form the backbone of what a theoretical prosthetic glider may need to accomplish. It needs to be able to move independently from the other wing on the same side, and flap! Either to provide lift or to help steer. Now, let’s get onto

Chapter 2: Construction of a Second Wing.

I say as if there would be one construction. Because. You know. It’s a mobility aid. There would be varying levels of need and thus varying types made so let’s go through them in rough order of least involved to most involved. Anyways I’m still not an engineer so uh fuck.

but first we have to start with the common elements. While I tend to think normal gliders for people without wings are unframed devices, I firmly believe that tengu wing prosthetics (which I’m going to call second wings I guess. I made up that name for the chapter title but do like it) are articulated framed constructions. Realistically I think bamboo would grow in Inazuma despite it not being there in game because trees can’t appear in two regions if they don’t have fruit, but, I think bamboo frames are the most common material due to its lightness.

I was originally going to draw pictures depicting the framing but it’s too late and I’m comfy cozy in bed, because past midnight is the only time I write insanely long tumblr posts. Diagrams may be added later but please use your imagination for now.

ideally I think the frame would follow the leading edge of the wing, acting almost as a second skeleton in order to minimize motions the wing is incapable of, and to provide a way to attach these things to the body harness. Realistically a frame on just one side of the wing may be impractical, and if that is the case then the wing is probably fully surrounded by a light bamboo frame. This probably depends on the needs of the user.

My general thought on the design of these would be a wing by wing approach. The trailing edge of the wings are not sewn close all the way, allowing the user to slide their wing in from the bottom before closing it with snaps, buttons, knots, etc. The wing would then be connected at the… shoulder I guess? The back? By an attachment to a harness. This prevents the wing cover from loosening or moving mid flight and secures the wooden framing against the skeletal structure. The idea would then be that a user could flap their wing normally, but with a larger impact than their wing could usually provide. The wing by wing nature of this general design allows for users to only have 1/4 wings be a second wing, or as many as they need in whichever combo. A more permanent harness attachment would likely be used in those who need both wings in a pair or both pairs, though the single wing approach may also be more practical for those with mobility issues in their wings. Basically, if the problem is lift generation, you can retrofit a wing over top and have a new wing! User cases: those with problems to wing shape (caused by injury or congenital) that hampers flight potential. Tengu with any other problem that does not limit range of motion below what one would typically need to fly with. See chapter 3 for more detail, because I do have a reason why this is the version I have thought about the most.

But speaking of those with mobility problems. What about people who can’t move their wings to the extent needed to fly typically. This is a much harder problem to solve with a second wing obviously, but I have had a few thoughts. To begin, these ones are definitely probably closer in framing to a full frame, because the frame will likely have to act as a brace. This is also the time to tell you I’m not a physical therapist. Anyways I don’t know how to solve this problem but there are a few options

A) the glider acts more like a brace and solid wing. The tengu’s wing(s) is still inside but does not bend, and is likely supported by more internal straps to fasten their wings tighter to the bamboo framing . This likely limits the ability to fly as flapping would not be an option. Though in individuals with upper wing injuries that limit mobility, I really do thing external control with strings controlled by arms or other body parts may be an option for sharp steering that is hard to do by body position alone.

B) Single wing injuries may be able to have rigging of some sort to have the motion of the opposite wing move the injured wing. This would likely be better if the injured wing was tucked away somewhere else and a new wooden boned wing was created.

use cases: those with atrophied ring muscles (though they may be able to move to previous one over time. Those with injuries limiting range of motion.

The last category is for those missing parts of or entire wings. These prosthetics would be the most intense, and would involve not only rigging wings to be able to flap and move via strings or whatever but also a different attachment system custom made to the user’s body. This… I don’t have enough engineering knowledge to imagine this I’m gonna be honest.

Chapter 3: hey why have you even thought about this and how does it pertain to characters (you can stop I’m just oc rambling. But also Kujou Sara)

So I’m gonna be honest and say I have a genshin OC who is a tengu. She is learning to make second wings because her nephew (who is like her little brother!) is a half tengu, and thus his wings are too small and aren’t growing primary feathers at quite the rate to support flight. She thinks that flight is one of the essential qualities that makes a tengu a tengu and not just a human with wings. She thinks he should get to be a tengu, and is thus making prosthetics from scratch even though she is very much not educated to do so.

This would eventually also lead her to talking with Kujou Sara. Thinking about Kujou Sara is a large part of why I have the oc, and also why I basically made her to be a foil to Sara. I don’t think Sara can fly, due to combination atrophy from not using them since I doubt Takayuki would let her go flying really, and injury (from falling off a mountain and whatever else she may have accumulated). Now. I don’t think Sara would like the concept of a mobility aid but also, like, I think it would be good for her to get her feet off the ground and to not have anything bad happen. Kujou Sara should have nice things and maybe one of those things can be talking to someone more immersed in the culture you are disconnected from and discovering things about it. And getting a second opinion on the things that mark you as obviously non human despite your effort to be one.

Anyways make your ocs to explore all the things in a game the game won’t cover, such as: long term ramifications of that war they just had, Yokai culture and self identification of the label, Kujou Sara having screen time and development and even some good things happening to her, Tengu, and wind gliders.

p.s: most of this ramble is just my genshin worldbuilding as related to wind gliders. Thus mostly textiles.